background If schizophrenia and related disorders are diagnosed and treated early, symptoms will be less severe and the prognosis will be more favourable. There is little point in screening for schizophrenia in the general population because the illness has such a low incidence. However, we do need to find out whether it is meaningful to screen genetically impaired individuals (high risk group) and specific groups of psychiatric patients (ultra high risk group).
aim To survey the research into the (high and ultra high) risk factors for developing a first psychosis and to find out whether it makes good sense to screen certain groups of persons.
method We conducted extensive desk-research and a wide-ranging search of the literature from 1990 to 2004. The key words we used in our search were 'prodrome', 'high risk', 'ultra high risk', in conjunction with 'psychosis' and 'schizophrenia'.
results In the genetically impaired group risk factors for developing schizophrenia seem to be transient psychiatric problems in childhood, schizotypical traits, anxiety, behavioural problems in adolescence, being brought up in an unstable environment and producing deviant results in neurocognitive tests. Among the patients referred to a psychiatrist it is possible to identify a special group of patients with an ultra high risk of developing a psychosis. Within a year 40% of patients who had mild or short-term psychotic symptoms or who were genetically impaired adolescents with decreased functioning had developed a psychosis.
conclusion Screening all genetically vulnerable persons in the general population has no consequences for treatment. Early diagnosis by psychiatrists is certainly advisable. However, larger groups and longer studies are needed in order to demonstrate conclusively the preventive effect of interventions prior to a first psychosis.